The known fission nuclear reactor employs a fuel, such as uranium, to produce heat which is transferred to a generating apparatus, typically a turbine driven generator. A known uranium fuel is enriched uranium-235. A coolant medium is circulated through the reactor to absorb heat produced by the nuclear reaction to create steam much as in oil or gas steam-generating processes. The steam is directed to a turbine to drive a generator, and the steam is then condensed and reintroduced to the coolant stream as a liquid.
U.S. Pat. No. 3,222,255 (Maldague) teaches a circuit for a nuclear reactor wherein a distillation column is used for removing substances which are suspended or in solution in the coolant circuit. The coolant intentionally contains a substantial amount of heavy water.
It is known to use either light water (H.sub.2 O) or heavy water (D.sub.2 O) as the coolant medium. Light water is used because of its good heat transfer and abundance. A reactor using light water as a coolant is commonly known as a light-water reactor.
A significant problem with the known nuclear reactor is that the coolant medium becomes radioactive because of bombardment of the medium with neutrons produced by the nuclear reaction. When water is used as the coolant medium, the bombardment with neutrons produces tritium which is highly radioactive and dangerous. The production of tritium is a two-step process. First, light hydrogen accepts one neutron to produce deuterium (heavy hydrogen). Second, the heavy hydrogen accepts another neutron to become the heaviest known hydrogen, which is called tritium. The second reaction is much slower than the first.
The major technique of preventing escape of tritium is to seal the coolant medium so as to prevent its escape. It is impossible, however, to fully prevent escape of the coolant medium since there must be a pressure relief valve for those instances when the coolant medium becomes overheated. It is a major safety hazard for the reactor to overheat thus causing the pressure relief valve of the coolant circuit to open and release tritium into the atmosphere.